Ordnance data correcting apparatus



W I) N 0 4 Kiel Nov. 26, 1946. w. L. ABEL ORDNANCE DATA CORRECTING APPARATUS Filed April 9, 1943 56 REm/c T10 GEAR/N6 fill/I727 FlUJlQlLllQ.

Patented Nov. 26, 1 946 caret Room ORDNANCE DATA CORRECTING APPARATUS Walter L. Abel, Beverly, Mass., assignor to United Shoe Machinery Corporation, Flemington, N. J a corporation of New Jersey Application April 9, 1943, Serial No. 482,518

4 Claims.

This invention relates to apparatus for correcting ordnance data, for changes which may occur during the time interval between the determination of and the use of such data.

In the directing of gun fire toward moving targets, such as, for example, airplanes, it is the usual practice to employ a computing and predicting apparatus which is capable of providing data, such as, angle of train, angle of elevation and fuse value, for transmission to the gun or guns. When received, this data is used by the gun crew in aiming the gun and for setting the fuse on the shell. After the fuse has been set, in accordance with the received data, the shell is then placed in the gun and the gun is fired. Inasmuch as the fuse values are continuously changing, with the change in the computed time of flight of the shell to the predicted position of the target, it is necessary to introduce a correction for the so-called dead time, i. e., the time it takes the gun crew to load and to fire the shell after the fuse has been set, in order that the shell will explode at the desired point in its trajectory.

It is an object of this invention to provide improved apparatus for continuously introducing dead time corrections into ordnance data, such as, for example, fuse values, as they are determined and before they are transmitted to the it may be conditioned for automatically and con-' tinuously making appropriate corrections to the data, being fed into the apparatus, before it is transmitted to the point where it is to be used. In this manner the correcting apparatus may be readily adapted to the different dead times of various gun crews.

Other objects and features of the invention will become apparent from the reading of the following detailed description of an illustrated embodiment of the invention, shown in the accompanying drawing, and will be pointed out in the claims.

In the drawing,

Fig. 1 is a schematic view of apparatus embodying the invention;

Fig. 2 is a view in section of mechanism forming a part of the apparatus shown in Fig. 1; and

Fig. 3 is a view in side elevation of parts of the mechanism shown in Fig. 2.

Referring to Fig. 1, for the purpose of describing the invention, the embodiment therein illustrated is shown associated with a ballistic cam H) which forms a part of an ordnance computing and predicting mechanism, such as for example an anti-aircraft director, and similar to cam F, Fig. 1B of United States patent to Chafiee et al. No. 2,065,303. As will be understood by persons skilled in the art, the cam 10 is rotated and moved axially during the operation of the director to shift a follower [2 in accordance with the computed and predicted data, which, for the purpose of this description, will be considered as being fuse value. The bar I2 is provided with rack teeth which mesh with a gear l4, fast on a shaft 16, so that this shaft is rotated thereby. Accordingly, the shaft I 6 will assume different angular positions corresponding to the different fuse values, as they are determined by the output of the cam I0, and will have an angular velocity which is proportional to the rate of change in these fuse values.

The shaft l6 drives, through bevel gears I8 and 20, a shaft 22 that is connected to one of the side gears 24 of a differential 35. The other side gear 26 of this differential is connected to a shaft 2'8 which drives a self-synchronous transmitting motor 30. The leads 32 from this motor are connected to a self-synchronous receiving motor, not shown, located at the gun. A correcting shaft 34 is connected at one end to the carrier 36 of the differential 35, and at its other end to the carrier 38 of a second differential 43, having side gears 40 and 42. A dial 44,

carrying fuse value indicia, is also carried by the shaft 28. When the correcting shaft is not rotated, the fuse values, as determined by the cam II], will be transmitted from the shaft I6 to the shaft 22 and thence, through the differential 35, to the shaft 28 and the transmitting motor 30. However, by rotating the shaft 34, these fuse values may be modified or corrected, inasmuch as the rotation of shaft 34 will be algebraically added to the rotation of shaft 22 in the difierential 35. It will therefore be apparent, if the shaft 34 is rotated in accordance with the com-- puted change in fuse value during a given dead time interval, that shaft 28 will be rotated in accordance with the predicted fuse value determined by the cam 10 and corrected for the computed change in the fuse value which will occur during that dead time interval. I

For rotating the shaft 34 in accordance with the computed change in the fuse value during a given dead time interval, the following mechanism is provided. Extending from the side gear 42 of the differential 43 is a shaft 45 which carries a bevel gear 46. This bevel gear meshes with a bevel gear 48 which is secured to the bal1 carriage adjusting shaft 56 of a variable speed drive comprising a disk 50, a ball carriage 52 and a cylinder 54. The disk 50 is driven by a shaft 58 of a second variable speed drive comprising a cylinder 60, a disk 62 and a ball carriage 64. The disk 62 is driven by a constant speed electric motor 66. The ball carriage 64 is provided with an adjusting shaft 68, carrying a knurled knob I0, and is threaded through a block I2 from which a pointer 14 extends. This pointer travels past a scale I6 bearing indicia in terms of the dead time, and these indicia are so arranged with respect to the position of the ball carriage 64 that the cylinder 60 rotates at a speed proportional to the reciprocal of the dead time value on the scale which is opposite to the pointer I4.

In thevariable speed drive including the disk 50, which is driven by the cylinder 60 just mentioned, the cylinder 54 will rotate at a speed which is proportional to the product of the speed of the disk 50 multiplied by the displacement of the ball carriage 52 from the center of said disk, i. e., Vc, the speed of the cylinder 54 is proportional to Va, the speed of the disk 50, multiplied by d, the ball carriage displacement. This relationship may also be expressed, by transposing the term Vd, as follows: d is proportional to VG divided by Va. As before explained, Va is proportional to the reciprocal of the dead time to which the pointer I4 has been set. Hence, d is proportional to the product of Va multiplied by this dead time. It follows, therefore, that for any speed of the cylinder V6, the rotation of shaft 56, which is a measure of the displacement of the ball carriage 52, (2, will be proportional to the product of V multiplied by the dead time setting of the ball carriage 64, as indicated on the scale 16.

The dead time correction which is to be made, by the shaft 34, is the product of the dead time interval multiplied by the rate of change in the fuse values. A measure of this rate of change is present in the manner in which shaft I6 is rotated by the cam I0, That is to say, if the rate of change in the fuse values is uniform, this shaft will rotate at a uniform angular velocity, while, if the rate of change varies, the shaft I6 will be accelerated or decelerated, depending upon the direction in which the variation takes place. Hence, if the ball carriage 52 is continuously so adjusted that the speed of the cylinder 54, V0, matches that of the shaft I6, the amount .of rotation of the shaft 56 which was necessary to effect this matching, will be preportional to the product of .the speed of rotation of the shaft I6, rate of change of fuse value, multiplied by the dead time, and will be a measure of the correction desired.

The matching of the speed of rotation of the cylinder 54 to that of the shaft I6 is effected in the following manner. The shaft 56, by means of which the ball carriage 52 is adjusted to vary the speed of the cylinder 54, is connected, by means of suitable reduction gearing 80, to a reversible electric motor 82. The operation of this motor is controlled by means of two contacts 84 and 86, carried by a hub 81, which is secured to the shaft l6 by means of set screw 89, Fig. 3, and a third contact 88. The contacts 84 and 86 comprise headed screws which are threaded through ears 90 and 92 formed on an arm 94 which is integral with the hub 81. The hub and arm are .con-

structed of insulating material and two collector rings 96 and 98, mounted on the hub, are electrically connected to the contacts 84 and 86 by means of metallic strips I00 and I02, Fig. 3. Two lead wires I04 and I06 from the motor 82 are connected to these collector rings by means of brushes I08 and H0. The contact 88 is carried by an arm H2, formed integrally with a hub H4, and is electrically connected to a third collector ring I I6, mounted on this hub, by means of a lead wire I I8. Another lead Wire I 20 is connected to this ring by means of a brush I22. The lastmentioned lead wire is connected to one side of an electric circuit, the other side of which is connected to a third terminal on the motor, as shown in Fig. 1. The arrangement of these lead wires is such that when the contact 88 touches contact the motor 82 runs in one direction, and when it touches the other contact 92, the motor runs in the reverse direction. The hubs 81 and I I4 carry weights I40 and I42 for counterbalancing the arms 94 and I I2.

The hub H4 is rotatably mounted on a shouldered bushing I26 which is secured to a shaft I28, extending from the cylinder 54, by means of a set screw I30. Secured to this bushing, by means of a set screw I32, is a dial wheel I34 and between this dial wheel and the hub II4 there is a second dial wheel I36 rotatably mounted on the bushing. This second dial wheel is held in frictional engagement with the hub I I4 by means of a spring I 38 which has sliding contact with the dial wheel I34. Thus, While the dial I34 is fixed with respect to the shaft I28 and must rotate with it, the dial I36 and the hub .I I4, together with its arm H2 and .the contact 88, can move relatively thereto. Such relative rotation of the arm H2 and dial I36 with respect to shaft I 28 and dial 1 34 will occur whenever the speeds of the shafts I6 and H8 are not the same, since the contact 88, which is secured to the arm 94, will then engage either one or the other of the two contacts 84, 86, which are secured to the shaft I6. Under these conditions, the motor 82 will be started and, through reduction gear 80, will turn the shaft 56 to effect a displacement of the ball carriage 52. The electrical connections to the motor and to the contacts are so arranged that this displacement takes place in a direction to bring the speed of rotation of the cylinder 54 and the shaft I28 up or down to the speed of rotation of the shaft I6. When this has been done, the

contact 88 will move away from the contact 84 or 86 and the motor will come to a stop. Hence, should the speed of the shaft I6 vary, a corresponding change in the speed of the cylinder 54 will be effected, through the action of the motor 82 when contact is again made with either of the contacts 84 or 86. As before explained, the ratation of the shaft 56 is proportional to the product of dead time multiplied by the rate of change in the fuse values, i. e., the correction for dead time, and this correction is added algebraicallyin the differential 35 to the fuse values as they are determined by the cam I0. Corrections for observed errors may be made by means of a hand wheel I44, connected to the side gear 40 of the differential 43, these corrections being algebraically added to the dead time correction in this differential.

The operation of the correcting apparatus which has just been described should be apparent from what has been heretofore said and is briefly as follows: The knob I0 is turned to set the pointer I4 opposite to the appropriate dead time IHZUID I LEE.

indicia on the scale I6 and the constant speed motor 66 is started. Now, as the target is tracked by the operators of the predicting and computing mechanism with which the cam I is associated, the fuse values are continuously determined by means of this cam and the shaft I6 is caused to rotate in accordance with the changes in these fuse values. These values are transmitted to the transmitting motor 30 through the shafts 22, 28 and the differential 35. Assuming that the ball carriage 52 was at the center of the disk 50 so that the cylinder 54 and its shaft I28 were stationary, the rotation of the shaft I6 would then bring one or the other of the two contacts 84 or 86 into engagement with the contact 88 and the arm II2, together with the dial I36, would be rotated relatively to the bushing I26 and the dial I34. This difference in the speeds of the rotation of shafts I6 and I28 will be apparent by the relative movement of the dials I34 and I36. Immediately, however, the motor 82 will be started and the ball carriage 52 moved in the proper direction to cause the cylinder 54 to retate at the same speed as the shaft I6. When this has been done, the shaft 56 will have been rotated an amount proportional to a correction in fuse value which corresponds to the dead time interval and the rate of change in fuse value at that particular instant. This correction is transmitted to the motor 30 by means of the shaft 44, differential 43, shaft 34, differential 35 and shaft 28. Accordingly, the fuse value which is transmitted to the guns from the motor 30 is the value determined by the cam I0 plus a correction for dead time. As the speed of the shaft I6 varies, with changes in the fuse value resulting from changes in the predicted position of the target, adjustment of the ball carriage 52 is automatically effected, by the motor 82, so as to keep the speed of the cylinder 54 matched to that of the shaft I 6. As these adjustments are made, the resulting corrections are continuously computed, in the manner above described, and these corrections fed into the differential 35 by the shaft 34.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. Apparatus for correcting ordnance data for changes occurring during dead time comprising a fuse value computing and predicting device, means driven by said device in accordance with predicted fuse values, a shaft, driving connections between said means and said shaft whereby the shaft is rotated in accordance with changes in predicted fuse values, a variable speed drive having a driving element, a driven element and a movable speed varying element, means for driving said driving element at a speed proportional to the reciprocal of the dead time interval for which correction is to be made, independently driven power-operated means, having control means sensitive to differences between the ,speeds of said shaft and said driven element, for

automatically moving said speed varying element so as to cause said driven element to move in accordance with changes in the predicted fuse value, and means for combining the movements of the speed varying element with the rotation of said shaft.

2. Apparatus for correcting ordnance data for Search m changes occurring during dead time comprising a fuse value computing and predicting device, means driven by said device in accordance with predicted fuse values, a shaft, driving connections between said means and said shaft whereby the shaft is rotated in accordance with changes in predicted fuse values, a variable speed drive having a driving disc, a driven cylinder, a ball carriage and a rotatable shaft for moving the carriage, means for driving the disc at a speed proportional to the reciprocal of the dead time interval of which correction is to be made, independcntly driven power-operated means, having control means sensitive to differences between the speeds of said shaft and said driven cylinder, for automatically rotating said second-named shaft to move the carriage so as to cause the cylinder to rotate at the same speed as said firstnamed shaft and hence in accordance with the changes in the predicted fuse values, and means for combining the rotation of the two shafts.

3. Apparatus for correcting ordnance data for changes occurring during dead time comprising a fuse value computing and predicting device, means driven by said device in accordance with predicted fuse values, a shaft, driving connections between said means and said shaft whereby the shaft is rotated in accordance with changes in predicted fuse values, a variable speed drive having a driving disc, a driven cylinder carrying a shaft, and a ball carriage, means for driving the disc at a speed proportional to the reciprocal of the dead time interval for which correction is to be made, a rotatable shaft for moving the ball carriage, means for rotating said shaft so as to cause the cylinder to rotate at the same speed as the first-named shaft and hence in accordance with the changes in the predicted fuse values, said shaft rotating means including a motor and means associated with the first-named shaft and the shaft carried by the cylinder for controlling the operation of the motor, and a differential for combining the rotations of the ball carriage moving shaft with the rotations of the first-named shaft.

4. Apparatus for correcting ordnance data for changes occurring during dead time comprising a fuse value computing and predicting device, means driven by said device in accordance with predicted fuse values, a shaft, driving connections between said means and said shaft whereby the shaft is rotated in accordance with changes in predicted fuse values, a variable speed drive having a driving disc, a driven cylinder carrying a shaft, and a movable ball carriage, means for driving the disc at a speed proportional to the reciprocal of the dead time interval for which correction is to be made, a rotatable shaft for moving the ball carriage, means for rotating said shaft so as to cause the cylinder to rotate at the same speed as the first-named shaft and hence in accordance with the changes in the predicted fuse values, said shaft rotating means including an electric motor and contacts on the first-named shaft and on the shaft carried by the cylinder for controlling the operation of the motor, and a differential for combining th rotations of the ball carriage moving shaft with the rotations of the first-named shaft.

WALTER L. ABEL. 

